Identification of genes specifically deregulated in tumour cells could bring to light new tumour suppressors and oncogenes with potential clinical applications in diagnostics, prognostics, and therapeutics. In Applicant's co-pending PCT application PCT/NO09/000214 we describe a new target gene of retinoids, CXXC5, encoding a nuclear factor that we have functionally characterized for the first time and named RINF (Retinoid-Inducible Nuclear Factor).
Our data indicated that RINF plays an essential role during in vitro human hematopoiesis. Indeed, expression studies and gene silencing experiments both demonstrate RINF implication during terminal differentiation of myeloid leukemia cells (NB4 and HL60 cell lines), but also during myelopoiesis of normal hematopoietic progenitors (bone marrow CD34+ cells). In keeping with its essential role during terminal myeloid differentiation and its localization to chromosome 5q31.3, a region often deleted in myeloid leukaemia (acute myeloid leukaemia and myelodysplasia), we have also suggested RINF as a promising tumor suppressor candidate at that locus in some myeloid malignancies.
Because RINF expression is not restricted to the hematopoietic tissue and may also be involved in development and/or homeostasis of other tissues, we have investigated RINF expression in some solid tumours derived from different tissues.
We have shown in Applicant's co-pending PCT application PCT/NO09/000214 that this gene could have a deregulated expression in some malignant tissues compared to their normal tissues of origin. Indeed, RINF mRNA expression was examined in solid tumour samples from patients suffering from breast cancer, and RINF expression was significantly higher in breast tumours compared to normal breast tissues controls.